Emergency smoke disposal system for pressurized aircraft

Abstract

The present invention provides a convenient and reliable means to evacuate smoke from an interior cabin (30) of a pressurized aircraft (20) by providing a normally closed smoke evacuation outlet (102) in the skin (108) of the aircraft in fluid communication with a relatively large area smoke disposal chute (114) extending upwardly from the cabin's ceiling (50), whereby upon the activation of the outlet, the smoke (106) (that otherwise would rise to and collect below the ceiling of the cabin until the whole cabin is full of smoke) will be discharged into the external airstream, with the differential pressure between the relatively high pressure in the cabin and the relatively low pressure in the external atmosphere (particularly at the high cruising altitudes associated with the operation of modern transport aircraft) providing the actual motive power. Preferably, the outlet is designed to be opened automatically (110, 124) in response to smoke in the vicinity of the smoke disposal chute being detected by means of a conventional type of smoke detector (120). The chute between the ceiling and the outlet on the skin may also be provided with a manual means (132, 134) for blocking the further outflow of pressurized air through the skin outlet opening in the event that the apparatus has been activated inadvertently or in the event that the emergency is over.

I claim: 
     
       1. A smoke evacuation system for a vehicle comprising: a skin opening defined in an outer skin separating an   interior compartment within said vehicle from an exterior environment surrounding said vehicle, said interior being capable of being maintained at a positive differential pressure with respect to said exterior;   a cover plate for covering said opening and thereby preventing any flow of air therethrough;   means for ejecting said cover plate from said opening; and   a smoke disposal chute having a first end in fluid communication with a region within said compartment at which smoke may be expected to collect and a second end in fluid communication with said opening;   whereby when said cover plate is ejected from said opening, any smoke-laden air in said region will be forced through said opening and evacuated into said external environment as a result of said positive pressure differential.   
     
     
       2. The system of claim 1 further comprising a grille in the vicinity of said first end for preventing the blockage of said chute by foreign objects. 
     
     
       3. The system of claim 1, wherein said vehicle is a transport aircraft provided with an air conditioning pack for conditioning air from said external environment and introducing it under pressure into said interior compartment and with an overflow vent for providing an opening having a variable cross-sectional area in said skin of said aircraft for permitting a portion of said pressurized air to be controllably released to said external environment, and   wherein the effective cross-sectional area of said opening after said cover plate has been ejected is less than the effective area of said vent during normal operation of said pack, whereby even after said cover plate has been ejected and said smoke evacuation system opening activated, said air conditioning pack will be able to continue to maintain the conditioned air inside said compartment at a predetermined normal pressure.   
     
     
       4. The system of claim 1 wherein said ejecting means is activated in response to an electrical signal. 
     
     
       5. The system of claim 4 wherein said ejection means comprises an electrically activated pyrotechnic fuse embedded in said cover plate so as to separate a central portion of said cover plate from a peripheral portion upon said electrical signal being applied to said fuse. 
     
     
       6. The system of claim 4 further comprising a smoke detector circuit for generating said electrical signal upon the detection of smoke in said region. 
     
     
       7. The system of claim 1 further comprising means for at least partially blocking said chute after said cover plate has been ejected. 
     
     
       8. The system of claim 1 wherein the effective cross-sectional area of said second end is sufficiently small that said interior compartment will remain pressurized even after said cover plate has been ejected and said opening exposed. 
     
     
       9. The system of claim 8 wherein the effective cross-sectional area of said first end is substantially larger than the cross-sectional area of said second end whereby the velocity of said smoke-laden air will be significantly less in the vicinity of said region compared to that at said opening.